1. Field of the Invention
Corrosion under insulation is problematic in many environments. In oil and gas production plants, process plants, refineries, and chemical plants, for example, corrosion under insulation can be a serious threat to plant integrity. Management of the corrosion under insulation problem can be extremely challenging, because water ingress is difficult to reliably predict and many types of insulation systems can be affected. Additionally, regular inspection and maintenance is difficult and costly, typically involving removal of insulation from process piping. Sometimes, the inspection and maintenance techniques can require shutdown of the plant process.
2. Description of Related Art
Moisture sensors exist but have drawbacks that limit their usefulness in many environments susceptible to corrosion under insulation. Conventional moisture sensors, constructed as point devices using coated, metalized surfaces that undergo a change in electrical impedance when exposed to moisture, are not practical for use in a process environment. Some sensors measure rate of heat dissipation to determine moisture content in a medium, while other sensors measure changes in electrical resistance of an element exposed to moisture, but none of these sensors is practical for use in many process and plant environments. For example, some of these sensors are not particularly helpful in providing guidance as to specific areas of concern along, for example, sections of insulated pipe. Another moisture sensing technique detects hydrogel-induced micro bending in fibers, but such techniques also have limited applicability in process and plant environments. For example, such techniques can be limited to environments in which temperatures only rise to approximately 50° C.